The present invention relates generally to capacitor banks used in electrical power systems, and more specifically to a method of monitoring the health of a capacitor bank.
In an electric power transmission and distribution system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. Higher currents increase the energy lost in the distribution system and require larger wires the use of heavy duty equipment, which in turn adds to the cost. Therefore, to correct the power factor in electrical power transmission and distribution systems, capacitor banks are often employed.
A capacitor bank is an assembly of a number of capacitor strings connected in parallel with each other with each of the capacitor strings including a number of capacitors connected in series. Capacitor banks add reactive power to the AC mains supply. In three phase power distribution systems, the power factor of each phase may be separately corrected using capacitor banks dedicated to each phase. In one example, the capacitor bank for each phase may contain 1000 capacitors arranged in 50 parallel capacitor strings, each string containing 20 capacitors connected in series. A capacitor failure in such an arrangement may result in voltage imbalance, voltage control problems, harmonic frequency problems, and inefficient system operation, which may cause power outages.
Manual methods for identifying the faulty capacitors in a capacitor bank typically involve disconnecting the capacitors and subsequently testing them individually to determine or locate the faulty capacitors. This method is expensive, time consuming and requires the shutdown of capacitor bank, thus resulting in loss of power and revenue.
Thus there exists a need for methods and systems for monitoring the health of a capacitor bank.